linux-kernel - Re: mmap: is default non-populating behavior stable?

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Message-ID: <491070B5.2060209@nortel.com>
Date:	Tue, 04 Nov 2008 09:56:37 -0600
From:	"Chris Friesen" <cfriesen@...tel.com>
To:	Rik van Riel <riel@...hat.com>
CC:	Peter Zijlstra <peterz@...radead.org>,
	"Eugene V. Lyubimkin" <jackyf.devel@...il.com>,
	linux-kernel@...r.kernel.org, linux-mm <linux-mm@...ck.org>,
	hugh <hugh@...itas.com>
Subject: Re: mmap: is default non-populating behavior stable?

Rik van Riel wrote:
> Peter Zijlstra wrote:

>> The exact interaction of mmap() and truncate() I'm not exactly clear on.
> 
> Truncate will reduce the size of the mmaps on the file to
> match the new file size, so processes accessing beyond the
> end of file will get a segmentation fault (SIGSEGV).

I suspect Peter was talking about using truncate() to set the initial 
file size, effectively increasing rather than reducing it.

Chris
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